The invention relates to compounds of the formula I
cyclo-(aArg-aGly-aAsp-aX-aY)xe2x80x83xe2x80x83I
in which
aArg is Arg or aza-Arg,
aGly is Gly or aza-Gly,
aAsp is Asp or aza-Asp,
aX, aY in each case independently of one another are an amino acid residue selected from a group consisting of Ala, Asn, Asp, Arg, Cys, Gln, Glu, Gly, His, Ile, Leu, Lys, Met, Nle, Orn, Phe, Phg, Pro, Ser, Thr, Tic, Trp, Tyr, Val, NHxe2x80x94Qxe2x80x94COxe2x80x94
or
the corresponding aza-amino acids,
Q is alkylene having 1-6 C atoms,
where
in at least one of the amino acids mentioned in formula I the Cxcex1 carbon is replaced by nitrogen,
the amino acids mentioned can also be derivatized, and the amino acid residues are linked to one another in peptide fashion via the a-amino or aza group and xcex1-carboxyl groups,
and if there are radicals of optically active amino acids and amino acid derivatives, both the D and the L forms are included,
and their salts.
Similar compounds of cyclic peptides are disclosed, for example, in EP 0 632 053, DE 195 38 741 or EP 0 683 173.
The invention is based on the object of finding novel compounds having valuable properties, in particular those which can be used for the production of medicaments.
It has been found that the compounds of the formula I and their salts have very valuable pharmacological properties combined with good tolerability. They act especially as integrin inhibitors, in particular inhibiting the interactions of the xcex1v-, xcex23- or xcex25-integrin receptors with ligands, such as, for example, the binding of fibrinogen to the xcex23-integrin receptor. The compounds show particular activity in the case of the integrins xcex1vxcex21, xcex1vxcex23, xcex1vxcex25, xcex1IIbxcex23 and also xcex1vxcex26 and xcex1vxcex28, in particular potent selective inhibitors of the vitronectin receptor xcex1vxcex23 have been found.
This action can be demonstrated, for example, by the method which is described by J. W. Smith et al. in J. Biol. Chem. 265, 12267-12271 (1990). The dependence of the origin of angiogenesis on the interaction between vascular integrins and extracellular matrix proteins is described by P. C. Brooks, R. A. Clark and D. A. Cheresh in Science 264, 569-71 (1994).
The possibility of the inhibition of this interaction and thus for the initiation of apoptosis (programmed cell death) of angiogenic vascular cells by a cyclic peptide is described by P. C. Brooks, A. M. Montgomery, M. Rosenfeld, R. A. Reisfeld, T.-Hu, G. Klier and D. A. Cheresh in Cell 79, 1157-64 (1994).
Compounds of the formula I, which block the interaction of integrin receptors and ligands, such as, for example, of fibrinogen on the fibrinogen receptor (glycoprotein IIb/IIIa), prevent, as GPIIb/IIIa antagonists, the spread of tumour cells by metastasis. This is confirmed by the following observations:
The compounds can inhibit the binding of metalloproteinases to integrins and thus prevent the cells being able to utilize the enzymatic activity of the proteinase. An example is to be found in the inhibitability of the binding of MMP-2 (matrix metalloproteinase-2) to the vitronectin receptor xcex1vxcex23 by a cyclo-RGD peptide, as described in P. C. Brooks et al., Cell 85, 683-693 (1996).
The spread of tumour cells from a local tumour into the vascular system takes place through the formation of microaggregates (microthrombi) by interaction of the tumour cells with blood platelets. The tumour cells are screened by protection in the microaggregate and are not recognized by the cells of the immune system. The microaggregates can fix to vascular walls, by means of which a further penetration of tumour cells into the tissue is facilitated. Since the formation of the microthrombi is mediated by fibrinogen formation on the fibrinogen receptors on activated blood platelets, the GPIIa/IIIb antagonists can be regarded as effective metasis inhibitors.
The compounds of the formula I can be employed as pharmaceutical active compounds in human and veterinary medicine, in particular for the prophylaxis and/or therapy of thrombosis, myocardial infarct, arteriosclerosis, inflammations, apoplexy, angina pectoris, oncoses, osteolytic diseases such as osteoporosis, pathologically angiogenic diseases such as, for example, inflammations, ophthalmological diseases, diabetic retinopathy, macular degeneration, myopia, ocular histoplasmosis, rheumatoid arthritis, osteoarthritis, rubeotic glaucoma, ulcerative colitis, Crohn""s disease, atherosclerosis, psoriasis, restenosis after angioplasty, multiple sclerosis, viral infection, bacterial infection, fungal infection, in acute kidney failure and in wound healing for supporting the healing processes.
The compounds of the formula I can be employed as substances having antimicrobial activity in operations where biomaterials, implants, catheters or heart pacemakers are used.
They have an antiseptic action here. The efficacy of the antimicrobial activity can be demonstrated by the procedure described by P. Valentin-Weigund et al., in Infection and Immunity, 2851-2855 (1988).
Since the compounds of the formula I are inhibitors of fibrinogen binding and thus ligands of the fibrinogen receptors on blood platelets, they can be used in vivo as diagnostics for the detection and localization of thrombi in the vascular system, provided they are substituted, for example, by a radioactive or UV-detectable residue.
The compounds of the formula I can be used as inhibitors of fibrinogen binding and as effective auxiliaries for the study of the metabolism of blood platelets in different activation stages or of intra-cellular signal mechanisms of the fibrinogen receptor. The detectable unit of a xe2x80x9clabelxe2x80x9d to be incorporated, e.g. isotopic labelling by 3H, allows, after binding to the receptor, the mechanisms mentioned to be investigated.
In the compounds of the formula I, the amino acids present can be modified such that the Cxcex1 carbon is replaced by nitrogen, with retention of the side chain. In this case, these are so-called aza-amino acids. For example, in the aza-tripeptide below, consisting of the amino acids arginine, glycine and aspartic acid, the Cxcex1 carbon of the glycine is replaced by nitrogen. 
In the compounds of the formula I according to the invention, at least one amino acid is always present as an aza-amino acid.
The abbreviations of amino acid residues listed above and below stand for the radicals of the following amino acids:

If the abovementioned amino acids can occur in several enantiomeric forms, then above and below, e.g. as a constituent of the compounds of the formula I, all these forms and also their mixtures (e.g. the DL forms) are included. Furthermore, the amino acids can be provided, e.g. as a constituent of compounds of the formula I, with corresponding protective groups which are known per se.
So-called prodrug derivatives are also included in the compounds according to the invention, i.e. compounds of the formula I, modified with, for example, alkyl or acyl groups, sugars or oligopeptides, which are rapidly cleaved in the body to the active compounds according to the invention. These also include biodegradable polymer derivatives of the compounds according to the invention, as is described, for example, in Int. J. Pharm. 115, 61-67 (1995).
Amino acids whose configuration is not specifically indicated have the (S) or (L) configuration.
The invention further relates to a process for the preparation of compounds of the formula I according to claim 1 and of their salts, characterized in that
(a) a compound of the formula II
Hxe2x80x94Zxe2x80x94OHxe2x80x83xe2x80x83II
xe2x80x83in which
Z is xe2x80x94aArg-aGly-aAsp-aX-aYxe2x80x94, xe2x80x94aGly-aAsp-aX-aY-aArg, xe2x80x94aAsp-aX-aY-aArg-aGlyxe2x80x94, xe2x80x94aX-aY-aArg-aGly-aAspxe2x80x94or xe2x80x94aY-aArg-aGly-aAsp-aXxe2x80x94,
and aArg, aGly, aAsp, aX and aY have the meanings indicated in claim 1,
or a reactive derivative of a compound of the formula II is treated with a cyclizing agent,
or
b) a compound of the formula I is set free from one of its functional derivatives by treating with a solvolysing or hydrogenolysing agent,
and/or in that a basic or acidic compound of the formula I is converted into one of its salts by treating with an acid or base.
Above and below, the radicals aArg, aGly, aAsp, aX and aY have the meanings indicated in the formulae I and II, if not expressly stated otherwise.
In the above formulae, alkyl is preferably methyl, ethyl, propyl, isopropyl, butyl, isoburyl, sec-butyl or tert-butyl, and further also pentyl, 1-, 2- or 3-methylbutyl, 1,1-, 1,2- or 2,2-dimethylpropyl, 1-ethylpropyl, hexyl, 1-, 2-, 3- or 4-methylpentyl, 1,1-, 1,2-, 1,3-, 2,2-, 2,3- or 3,3-dimethylbutyl, 1-or 2-ethylbutyl, 1-ethyl-1-methylpropyl, 1-ethyl-2-methylpropyl, 1,1,2- or 1,2,2-trimethylpropyl.
Alkylene is preferably methylene, ethylene, propylene, butylene, pentylene or hexylene.
The amino acids and amino acid residues mentioned can also be derivatized, the N-methyl, N-ethyl, N-propyl, N-benzyl or C,-methyl derivatives being preferred. Derivatives of Asp and Glu are furthermore preferred, in particular the methyl, ethyl, propyl, butyl, tert-butyl, neopentyl or benzyl esters of the side chain carboxyl groups, and further also derivatives of Arg, which can be substituted on the xe2x80x94NHxe2x80x94C(xe2x95x90NH)xe2x80x94NH2 group by an acetyl, benzoyl, methoxycarbonyl or ethoxycarbonyl radical.
Amino protective group preferably denotes acetyl, propionyl, butyryl, phenylacetyl, benzoyl, toluyl, POA, methoxycarbonyl, ethoxycarbonyl, 2,2,2-trichloro-ethoxycarbonyl, Boc, 2-iodoethoxycarbonyl, CBZ (xe2x80x9ccarbobenzoxyxe2x80x9d), 4-methoxybenzyloxycarbonyl, Fmoc, Mtr or benzyl.
The compounds of the formula I can have one or more chiral centres and therefore occur in various stereoisomeric forms. The formula I includes all these forms.
Accordingly, the invention relates in particular to those compounds of the formula I in which at least one of the radicals mentioned has one of the preferred meanings indicated above. Some preferred groups of compounds can be expressed by the following subformulae Ia to Ic, which correspond to the formula I and in which the radicals not designated in greater detail have the meaning indicated under the formula I, but in which
in Ia) aArg is Arg,
aGly is aza-Gly,
aAsp is Asp
aX, aY in each case independently of one another are an amino acid residue selected from a group consisting of Ala, Asn, Asp, Arg, Cys, Gln, Glu, Gly, His, Ile, Leu, Lys, Met, Phe, Pro, Ser, Thr, Trp, Tyr, Val
or
the corresponding aza-amino acids, and the abovementioned amino acids can also be derivatized;
in Ib) aArg is Arg,
aGly is aza-Gly,
aAsp is Asp
aX is Gly, Phe, D-Phe or aza-Phe and
aY is Gly, Val, Leu, Pro, D-Val, D-Leu or
D-Pro
or
the corresponding aza-amino acids, and the amino acids mentioned can also be derivatized;
in Ic) aArg is Arg,
aGly is aza-Gly,
aAsp is Asp
aX is Gly, Phe or D-Phe and
aY is Gly, N-benzyl-Gly, Lys, D-Lys, Val,
D-Val,
or
the corresponding aza-amino acids,
and the amino acids mentioned can also be derivatized;
The compounds of the formula I and also the starting substances for their preparation are otherwise prepared by methods known per se, such as are described in the literature (e.g. in the standard works such as Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart), namely under reaction conditions which are known and suitable for the reactions mentioned. In this case, use can also be made of variants which are known per se but not mentioned here in greater detail.
If desired, the starting substances can also be formed in situ such that they are not isolated from the reaction mixture, but are immediately reacted further to give the compounds of the formula I.
Compounds of the formula I can preferably be obtained by cyclization of compounds of the formula II under the conditions of a peptide synthesis. In this case, the reaction is expediently carried out by customary methods of peptide synthesis, such as are described, for example, in Houben-Weyl, l.c., Volume 15/II, pages 1 to 806 (1974).
The reaction preferably takes place in the presence of a dehydrating agent, e.g. of a carbodiimide such as DCCI or EDCI, and further, for example, propanephosphonic anhydride (cf. Angew. Chem. 92, 129 (1980)), diphenylphosphoryl azide or 2-ethoxy-N-ethoxy-carbonyl-1,2-dihydroquinoline, in an inert solvent, e.g. a halogenated hydrocarbon such as dichloromethane, an ether such as tetrahydrofuran or dioxane, an amide such as DMF or dimethylacetamide, a nitrile such as acetonitrile, in dimethyl sulfoxide or in the presence of these solvents, at temperatures between approximately xe2x88x9210 and 40xc2x0, preferably between 0 and 30xc2x0. In order to promote intramolecular cyclization ahead of intermolecular peptide bonding, it is expedient to work in dilute solutions.
Depending on the conditions used the reaction time is between a few minutes and 14 days.
Instead of compounds of the formula II, it is also possible to employ derivatives of compounds of the formula II, preferably a preactivated carboxylic acid, or a carboxylic acid halide, a symmetrical or mixed anhydride or an active ester. Radicals of this type for the activation of the carboxyl group in typical acylation reactions are described in the literature (e.g. in the standard works such as Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart). Activated esters are expediently formed in situ, e.g. by addition of HOBt or N-hydroxysuccinimide.
As a rule, the reaction is carried out in an inert solvent, when using a carboxylic acid halide in the presence of an acid-binding agent, preferably of an organic base such as triethylamine, dimethylaniline, pyridine or quinoline.
The addition of an alkali metal or alkaline earth metal hydroxide, carbonate or bicarbonate or of another salt of a weak acid of the alkali metals or alkaline earth metals, preferably of potassium, sodium, calcium or caesium, may also be favourable.
As a rule, the starting substances of the formula II are novel. They can be prepared by known methods of peptide synthesis. Linear peptides can be synthesized, for example, according to Merrifield (Angew. Chem. 97, 801-812 1985) on a solid phase, a swellable polystyrene resin.
The compounds of the formula I can further be obtained by setting them free from their functional derivatives by solvolysis, in particular hydrolysis, or by hydrogenolysis.
Preferred starting substances for the solvolysis or hydrogenolysis are those which, instead of one or more free amino and/or hydroxyl groups, contain corresponding protected amino and/or hydroxyl groups, preferably those which, instead of an H atom which is bonded to an N atom, carry an amino protective group, e.g. those which correspond to the formula I but instead of an NH2 group contain an NHRxe2x80x2 group (in which Rxe2x80x2 is an amino protective group, e.g. Boc or CBZ).
Starting substances are furthermore preferred which, instead of the H atom of a hydroxyl group, carry a hydroxyl protective group, e.g. those which correspond to the formula I but instead of a hydroxyphenyl group contain an Rxe2x80x3O-phenyl group (in which Rxe2x80x3 is a hydroxyl protective group).
A plurality ofxe2x80x94identical or differentxe2x80x94protected amino and/or hydroxyl groups can also be present in the molecule of the starting substance. If the protective groups present are different from one another, in many cases they can be selectively removed.
The expression xe2x80x9camino protective groupxe2x80x9d is generally known and relates to groups which are suitable for protecting (for blocking) an amino group from chemical reactions, but which are easily removable after the desired chemical reaction has been carried out at other positions in the molecule. Typical of such groups are, in particular, unsubstituted or substituted acyl, aryl, aralkoxymethyl or aralkyl groups. Since the amino protective groups are removed after the desired reaction (or reaction sequence), their nature and size is otherwise not critical; however, those having 1-20, in particular 1-8, C atoms are preferred. The expression xe2x80x9cacyl groupxe2x80x9d is to be interpreted in the widest sense in connection with the present process. It includes acyl groups derived from aliphatic, araliphatic, aromatic or heterocyclic carboxylic acids or sulfonic acids and also, in particular, alkoxycarbonyl, aryloxycarbonyl and especially aralkoxycarbonyl groups. Examples of acyl groups of this type are alkanoyl such as acetyl, propionyl, butyryl; aralkanoyl such as phenylacetyl; aroyl such as benzoyl or toluyl; aryloxyalkanoyl such as POA; alkoxycarbonyl such as methoxycarbonyl, ethoxycarbonyl, 2,2,2-trichloroethoxycarbonyl, Boc, 2-iodoethoxycarbonyl; aralkyloxycarbonyl such as CBZ (xe2x80x9ccarbobenzoxyxe2x80x9d), 4-methoxybenzyloxycarbonyl, Fmoc; arylsulfonyl such as Mtr. Preferred amino protective groups are Boc and Mtr, and further CBZ, Fmoc, benzyl and acetyl.
The expression xe2x80x9chydroxyl protective groupxe2x80x9d is likewise generally known and relates to groups which are suitable for protecting a hydroxyl group from chemical reactions, but which are easily removable after the desired chemical reaction has been carried out at other positions in the molecule. Typical of such groups are the abovementioned unsubstituted or substituted aryl, aralkyl or acyl groups, and furthermore also alkyl groups. The nature and size of the hydroxyl protective groups is not critical, since they are removed again after the desired chemical reaction or reaction sequence; groups having 1-20, in particular 1-10, C atoms are preferred. Examples of hydroxyl protective groups are, inter alia, benzyl, p-nitrobenzoyl, p-toluenesulfonyl, tert-butyl and acetyl, benzyl and tert-butyl being particularly preferred. The COOH groups in aspartic acid and glutamic acid are preferably protected in the form of their tert-butyl esters (e.g. Asp(OBut)).
The compounds of the formula I are set free from their functional derivativesxe2x80x94depending on the protective group usedxe2x80x94e.g. using strong acids, expediently using TFA or perchloric acid, but also using other strong inorganic acids such as hydrochloric acid or sulfuric acid, strong organic carboxylic acids such as trichloroacetic acid or sulfonic acids such as benzene-or p-toluenesulfonic acid. The presence of an additional inert solvent is possible, but not always necessary. Suitable inert solvents are preferably organic solvents, for example carboxylic acids such as acetic acid, ethers such as tetrahydrofuran or dioxane, amides such as DMF, halogenated hydrocarbons such as dichloromethane, and furthermore also alcohols such as methanol, ethanol or isopropanol, and also water. Mixtures of the abovementioned solvents are furthermore suitable. TFA is preferably used in an excess without addition of a further solvent, perchloric acid in the form of a mixture of acetic acid and 70% perchloric acid in the ratio 9:1. The reaction temperatures for the cleavage are expediently between approximately 0 and approximately 50xc2x0, preferably the cleavage is carried out between 15 and 30xc2x0 (room temperature).
The groups Boc, OBut and Mtr can, for example, preferably be removed using TFA in dichloromethane or using approximately 3 to 5 N HCl in dioxane at 15-30xc2x0, the Fmoc group using an approximately 5 to 50% solution of dimethylamine, diethylamine or piperidine in DMF at 15-30xc2x0.
The trityl group is employed for the protection of the amino acids histidine, asparagine, glutamine and cysteine. Removal is carried out, depending on the desired final product, using TFA/10% thiophenol, the trityl group of all amino acids mentioned being removed, when using TFA/anisole or TFA/thioanisole only the trityl group of His, Asn and Gln being removed, while it remains on the Cys side chain.
Hydrogenolytically removable protective groups (e.g. CBZ or benzyl) can be removed, for example, by treating with hydrogen in the presence of a catalyst (e.g. of a noble metal catalyst such as palladium, expediently on a support such as carbon). Suitable solvents here are those indicated above, in particular, for example, alcohols such as methanol or ethanol or amides such as DMF. As a rule, the hydrogenolysis is carried out at temperatures between approximately 0 and 100xc2x0 and pressures between approximately 1 and 200 bar, preferably at 20-30xc2x0 and 1-10 bar. Hydrogenolysis of the CBZ group is readily carried out, for example, on 5 to 10% Pd/C in methanol or using ammonium formate (instead of hydrogen) on Pd/C in methanol/DMF at 20-30xc2x0.
A base of the formula I can be converted into the associated acid addition salt using an acid, for example by reaction of equivalent amounts of the base and of the acid in an inert solvent such as ethanol and subsequent evaporation. In particular, acids which yield physiologically acceptable salts are suitable for this reaction. Thus inorganic acids can be used, e.g. sulfuric acid, nitric acid, hydrohalic acids such as hydrochloric acid or hydrobromic acid, phosphoric acids such as orthophosphoric acid, sulfamic acid, and furthermore organic acids, in particular aliphatic, alicyclic, araliphatic, aromatic or heterocyclic mono-or polybasic carboxylic, sulfonic or sulfuric acids, e.g. formic acid, acetic acid, propionic acid, pivalic acid, diethylacetic acid, malonic acid, succinic acid, pimelic acid, fumaric acid, maleic acid, lactic acid, tartaric acid, malic acid, citric acid, gluconic acid, ascorbic acid, nicotinic acid, isonicotinic acid, methane- or ethanesulfonic acid, ethanedisulfonic acid, 2-hydroxyethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, naphthalenemono- and disulfonic acids, laurylsulfuric acid. Salts with physiologically unacceptable acids, e.g. picrates, can be used for the isolation and/or purification of the compounds of the formula I.
On the other hand, an acid of the formula I can be converted into one of its physiologically acceptable metal or ammonium salts by reaction with a base. Possible salts in this case are, in particular, the sodium, potassium, magnesium, calcium and ammonium salts, and furthermore substituted ammonium salts, e.g. the dimethyl-, diethyl- or diisopropylammonium salts, monoethanol-, diethanol- or diisopropylammonium salts, cyclohexyl- or dicyclohexylammonium salts, dibenzylethylenediammonium salts, and furthermore, for example, salts with arginine or lysine.
The invention further relates to the use of the compounds of the formula I and/or their physiologically acceptable salts for the production of pharmaceutical preparations, in particular in a non-chemical way. In this context, they can be brought into a suitable dose form together with at least one solid, liquid and/or semi-liquid excipient or auxiliary and, if appropriate, in combination with one or more other active compounds.
The invention furthermore relates to pharmaceutical preparations comprising at least one compound of the formula I and/or one of its physiologically acceptable salts.
These preparations can be used as medicaments in human or veterinary medicine. Suitable excipients are organic or inorganic substances which are suitable for enteral (e.g. oral) or parenteral administration, topical application or administration in the form of an inhalation spray and do not react with the novel compounds, for example water, vegetable oils, benzyl alcohols, alkylene glycols, polyethylene glycols, glyceryl triacetate, gelatin, carbohydrates such as lactose or starch, magnesium stearate, talc, petroleum jelly. In particular, tablets, pills, coated tablets, capsules, powders, granules, syrups, juices or drops are used for oral administration, suppositories are used for rectal administration, solutions, preferably oily or aqueous solutions, and furthermore suspensions, emulsions or implants are used for parenteral administration, and ointments, creams or powders are used for topical application. The novel compounds can also be lyophilized and the lyophilizates obtained used, for example, for the production of injection preparations. The preparations indicated can be sterilized and/or can contain auxiliaries such as lubricants, preservatives, stabilizers and/or wetting agents, emulsifiers, salts for affecting the osmotic pressure, buffer substances, colourants, flavourings and/or one or more further active compounds, e.g. one or more vitamins. For administration as an inhalation spray, sprays can be used which contain the active compound either dissolved or suspended in a propellant or propellant mixture (e.g. CO2 or chlorofluorohydrocarbons). Expediently, the active compound is in this case used in micronized form, it being possible for one or more additional physiologically tolerable solvents, e.g. ethanol, to be present. Inhalation solutions can be administered with the aid of customary inhalers.
The compounds of the formula I and their physiologically acceptable salts can be used as integrin inhibitors in the control of illnesses, in particular of thromboses, cardiac infarct, coronary heart diseases, arteriosclerosis, tumours, osteoporosis, inflammations and infections.
The compounds of the formula I according to claim 1 and/or their physiologically acceptable salts are also used in pathological processes which are supported or propagated by angiogenesis, in particular in tumours or rheumatoid arthritis.
In this case, the substances according to the invention can as a rule be administered in analogy to other known, commercially available peptides, but in particular in analogy to the compounds described in U.S. Pat. No. 4,472,305, preferably in doses between approximately 0.05 and 500 mg, in particular between 0.5 and 100 mg per dose unit. The daily dose is preferably between approximately 0.01 and 2 mg/kg of body weight. The specific dose for each patient depends, however, on all sorts of factors, for example on the efficacy of the specific compound employed, on the age, body weight, general state of health, sex, on the diet, on the time and route of administration, on the excretion rate, pharmaceutical combination and severity of the particular disorder to which the therapy applies. Parenteral administration is preferred.
The compounds of the formula I can furthermore be used as integrin ligands for the preparation of columns for affinity chromatography for the preparation of integrins in pure form. The ligand, i.e. a compound of the formula I, is in this case coupled to a polymeric support via an anchor function, e.g. the carboxyl group of Asp.
Suitable polymeric supports are the polymeric solid phases, preferably having hydrophilic properties, known per se in peptide chemistry, for example crosslinked polysugars such as cellulose, Sepharose or SEPHADEX(copyright) (a crosslinked polymer of dextran), acrylamides, polymer based on polyethylene glycol or Tentakel(copyright) polymers (anion ion exchangers).
The materials for affinity chromatography for integrin purification are prepared under conditions such as are customary and known per se for the condensation of amino acids.
The compounds of the formula I contain one or more chiral centres and can therefore be present in racemic or in optically active form, Racemates obtained can be separated into the enantiomers mechanically or chemically by methods known per se. Preferably, diastereomers are formed from the racemic mixture by reaction with an optically active resolving agent. Suitable resolving agents are, for example, optically active acids, such as the D and L forms of tartaric acid, diacetyltartaric acid, dibenzoyltartaric acid, mandelic acid, malic acid, lactic acid or the various optically active camphorsulfonic acids such as xcex2-camphorsulfonic acid. Also advantageous is an enantiomer resolution with the aid of a column packed with an optically active resolving agent (e.g. dinitrobenzoylphenylglycine); a suitable eluent is, for example, a mixture of hexane/isopropanol/acetonitrile e.g. in the volume ratio 82:15:3.
Of course, it is also possible to obtain optically active compounds of the formula I by the methods described above by using starting substances which are already optically active.
All temperatures above and below are indicated in xc2x0 C. In the following examples, xe2x80x9ccustomary working upxe2x80x9d means: if necessary, water is added, the mixture is adjusted, if necessary, to a pH of between 2 and 10, depending on the constitution of the final product, and extracted with ethylacetate or dichloromethane, the organic phase is separated off, dried over sodium sulfate and evaporated, and the residue is purified by chromatography on silica gel and/or by crystallization. Rf values on silica gel; eluent: n-butanol/acetic acid/water 3:1:1 (A), chloroform/memthanol 9:1 (B)
RTxe2x80x94retention time (minutes) on HPLC in the following systems:
column: Nucleosil -5-C18 column (250xc3x974; 5 xcexcm); eluents used were gradients of acetonitrile with 0.9% TFA and water with 1.1% TFA (data in each case in per cent by volume of acetonitrile) detection at 220 and 254 nm.
The separation of the diastereomers is preferably carried out under the conditions indicated.
Mass spectrometry (MS): FAB (Fast Atom Bombardment) (M+H)+.